Accelerated Recovery During Negotiation Between a Media Gateway and a Media Gateway Controller

ABSTRACT

A method is disclosed that enables an improved technique for recovering from an error scenario encountered during a call setup that involves a malfunctioning media gateway and the corresponding media gateway controller. The media gateway first detects a malfunction that affects a digital signal processing resource. The media gateway then proactively selects a processing resource available elsewhere at the gateway. The media gateway selects the new processing resource based on criteria that include: i) the capabilities that were identified to handle the packet stream at the affected (faulty) processor; ii) the capabilities of the IP terminal originating the packet stream that is being moved; and iii) the Internet Protocol address of the affected processing resource. Advantageously, an effort is made to avoid having to inform the media gateway controller of the move, thereby minimizing any discontinuity in each packet stream and minimizing the time and processing that are required to establish the call.

FIELD OF THE INVENTION

The present invention relates to telecommunications in general, and,more particularly, to accelerating the recovery when a fault occurs at amedia gateway during initial call setup.

BACKGROUND OF THE INVENTION

A modern telecommunications system often comprises one or more switchedtelephone networks and one or more Internet Protocol-based packetnetworks. These two different types of networks are interconnected by amedia gateway, which acts as a translator between the two types ofnetworks. The media gateway enables multimedia communications, such asvoice and video, over multiple transport protocols end to end.

Because the media gateway connects different types of networks, one ofits main functions is to convert between the different transmission andcoding techniques used across the different networks. For example, aVoice-over-Internet-Protocol-capable (VoIP-capable) media gatewayperforms the conversion between time division multiplexed voice mediathat originate at a switched telephone network telecommunicationsterminal and VoIP datagram media that is intended for an InternetProtocol network terminal, as part of a telephone conversation betweentwo parties; of course, the media gateway has to perform the conversionin the other direction as well. Other functions that the media gatewayprovides are echo cancellation, tone detection, tone generation (e.g.,dual tone multi-frequency tones, etc.), and conferencing.

Since a packet stream that is received from the Internet Protocolnetwork comprises data packets and control packets, which containaddressing information, the VoIP media gateway converts the receivedpackets to a time division multiplexed stream while processing thecontrol packets. The media gateway must perform the conversion in atimely manner to minimize the possibility of packet loss, which thelistening party on a call might perceive. To handle all of the packetsresponsively and without unacceptable delay or jitter, the media gatewayuses digital signal processors, which are dedicated devices that arecapable of the high-speed packet processing that is required for theconversion. Each digital signal processor comprises multiple processingresources, such as processing channels, to handle multiple calls and thedifferent conversion formats across the calls. For example, theconversion formats might be distinguished from one another by codectype, encryption algorithm, payload values, addressing information, orredundancy in the information transmitted. Protocol standards andformulas exist that govern these properties, such as G.711 and G.729compression/decompression algorithms. Similarly, the media gateway mustalso perform the conversion in the other direction from a time divisionmultiplexed stream to Internet Protocol packets in a timely manner.

One or more media gateways are controlled by a media gateway controller,which provides the call control and signaling functionality for eachmedia gateway and across media gateways. Communication between mediagateways and media gateway controllers is achieved by means of protocolssuch as H.248, Media Gateway Control Protocol (MGCP), and so forth.During a call initialization that involves an Internet Protocol (IP)terminal, the media gateway controller provides to the IP terminal theIP address of the media gateway resource that is handling the call. Thisenables the IP terminal to specify the proper destination address of thepackets that it originates and to recognize the packets that are beingsent to the terminal. Alternatively, instead of a call involving an IPterminal, the call could involve another media gateway that exchangespackets with the aforementioned media gateway resource that is handlingthe call.

The media gateway controller and a selected media gateway work togetherto set up a call between a telecommunications terminal in one type ofnetwork, such as the IP network, and a terminal in another type ofnetwork, such as the switched telephone network. First, as part of aresource negotiation the media gateway controller requests the selectedmedia gateway that it has selected to provide a list of available signalprocessing resources from among those that are supported by the IPterminal. The media gateway determines what resources are available andwhat conversion formats can be accommodated by those resources.Normally, the media gateway controller proceeds to select a resource,provides the necessary addressing information to the IP terminalinvolved in the call, and responds back to the media gateway with anindication of the assigned resource.

However, between the time at which a digital signal processor resourceis identified by the media gateway to possibly handle the call and thetime at which the media gateway receives an indication that thecontroller has assigned the resource to the call, a malfunction mighthave occurred that prevents the signal processor from handling thepackets of the call. Although a mechanism does exist to inform the mediagateway controller that an error has occurred, one or more of the callparties are consequently subjected to a prolonged period during whichnothing is heard on the bearer channel. This undesirable condition canresult in user dissatisfaction.

What is needed is an improved technique for recovering from thedescribed error scenario that involves a malfunctioning media gatewayand the corresponding media gateway controller, without some of thedisadvantages in the prior art.

SUMMARY OF THE INVENTION

The present invention enables an improved technique for recovering froman error scenario encountered during a call setup that involves amalfunctioning media gateway and the corresponding media gatewaycontroller, without some of the disadvantages in the prior art. Inaccordance with the illustrative embodiment of the present invention,the media gateway first detects, during the setup interval of a newcall, a malfunction that affects one or more digital signal processingresources, such as processing channels, including the resource that wasidentified to handle the call's packet stream. The media gateway thenproactively selects a processing resource available elsewhere at themedia gateway to process the affected stream. The media gateway selectsthe new processing resource based on one or more criteria, including: i)the capabilities that were identified to handle the packet stream at theaffected (faulty) processor; ii) the capabilities of the IP terminaloriginating the affected packet stream; and iii) the Internet Protocoladdress of the affected processing resource. Advantageously, an effortis made to avoid having to inform the media gateway controller of themove, thereby minimizing any discontinuity in each packet stream andminimizing the time and processing that are required to establish thecall.

The media gateway of the illustrative embodiment comprises multiplesignal processing units, each unit containing a plurality of digitalsignal processors and each unit being uniquely addressable by anInternet Protocol address. In addition, each signal processing unit hasits own address space of User Datagram Protocol (UDP) port numbers, eachport number being allocable to a packet stream being processed by adigital signal processor channel on the signal processing unit. Bysimply reassigning the port number currently being used to process thepacket stream to another processor on the same signal processing unit,the media gateway of the illustrative embodiment sidesteps having toinform the media gateway controller; this is because only the gatewayneeds to know of the new assignment of the port number to properly routethe packet stream. And when a processing resource is available, but noton the current signal processing unit, the media gateway of theillustrative embodiment transmits a change request message to the mediagateway controller, specifying (i) the IP address of the new signalprocessing unit and (ii) the new port, so that the controller can informthe IP terminal of the change in IP address and port. By using thistwo-tiered approach, the media gateway is able to accelerate thenegotiation of processing resources between the media gateway and themedia gateway controller, when a fault occurs during a critical time inthe call setup process.

The illustrative embodiment of the present invention comprises:detecting a first malfunction, wherein the first malfunction affects afirst processing resource in a first signal processor in a firstdata-processing system; receiving a first indication, which indicatesthat the first processing resource has been assigned to handle a firstpacket stream, wherein the first processing resource is addressable by afirst port number, and wherein the first port number exists in theaddress space of a first plurality of signal processors that comprisesthe first signal processor; selecting a second processing resource tohandle the first packet stream, wherein the selection occurs as theresult of (i) the detection of the first malfunction and (ii) thereceiving of the first indication; and reassigning the first port numberto the second processing resource.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic diagram of telecommunications system 100, inaccordance with the illustrative embodiment of the present invention.

FIG. 2 depicts the salient components of media gateway 101-p in system100.

FIG. 3 depicts the salient components of packet processor/interface 203at media gateway 101-p.

FIG. 4 depicts a message flow diagram of an information exchange betweenInternet Protocol telecommunications terminal 104-1, media gatewaycontroller 103, and media gateway 101-1, in accordance with theillustrative embodiment of the present invention, when signal processingresources are available with the IP address replied by the media gatewayat the start of negotiation.

FIG. 5 depicts a first flowchart of the salient tasks that involvereassigning a second processing resource to handle a call's packetstream, in accordance with the illustrative embodiment of the presentinvention.

FIG. 6 depicts a second flowchart of the salient tasks that involvereassigning a second processing resource to handle a call's packetstream, in accordance with the illustrative embodiment of the presentinvention.

FIG. 7 depicts a message flow diagram of an information exchange betweenmedia gateway 101-1 and message gateway controller 103, in accordancewith the illustrative embodiment of the present invention, when signalprocessing resources are not available with the IP address replied bythe media gateway at the start of negotiation.

DETAILED DESCRIPTION

FIG. 1 depicts a schematic diagram of telecommunications system 100, inaccordance with the illustrative embodiment of the present invention.Telecommunications system 100 comprises:

-   -   i. media gateways 101-1 through 101-P, wherein P is a positive        integer;    -   ii. Internet Protocol (IP) packet network 102;    -   iii. media gateway controller 103;    -   iv. IP telecommunications terminals 104-1 through 104-Q, wherein        Q is a positive integer;    -   v. Public Switched Telephone Network (PSTN) 105;    -   vi. PSTN telecommunications terminals 106-1 through 106-S,        wherein S is a positive integer;    -   vii. local enterprise network 107; and    -   viii. analog telecommunications terminals 108-1 through 108-T,        wherein T is a positive integer.

All of the elements depicted in FIG. 1 are interconnected as shown.

Media gateway 101-p, for p=1 through P, is a data-processing system thatcomprises media gateway functionality that is known in the art, actingas a translator between two types of networks in well-known fashion; asdepicted, media gateway 101-1 acts as a translator between InternetProtocol network 102 and Public Switched Telephone Network 105 orbetween network 102 and local enterprise network 107, which networks aredescribed below. The salient components of media gateway 101-p aredescribed below and with respect to FIGS. 2 and 3. Media gateway 101-penables multimedia communications, such as voice and video, overmultiple transport protocols from one terminal in one network to anotherterminal in another network, in part by working in concert with mediagateway controller 103 to set up, maintain, and terminate calls.

Because media gateway 101-p, including media gateway 101-1, connectsdifferent types of networks, one of its main functions is to convertbetween the different transmission and coding techniques uses across thedifferent networks. In accordance with the illustrative embodiment,media gateway 101-1 is a Voice-over-Internet-Protocol-capable(VoIP-capable) media gateway that performs the conversion between timedivision multiplexed voice signals that originate at a switchedtelephone network telecommunications terminal, such as one of terminals106-1 through 106-S, and VoIP signals that are intended for an InternetProtocol network terminal, such as one of IP terminals 104-1 through104-Q, as part of a telephone conversation between two parties. Mediagateway 101-1 performs the conversion in the reverse direction as well(i.e., from an IP terminal to a PSTN terminal) and is able to performbidirectional conversion for multiple calls concurrently.

Media gateway 101-1 in the illustrative embodiment comprises voicepacket-processing functionality. However, as those who are skilled inthe art will appreciate, in some alternative embodiments of the presentinvention, media gateway 101-p is able to process packets that containother types of bearer information such as video.

Media gateway 101-p executes the tasks described below and with respectto FIGS. 4 through 7 in supporting the functionality of the illustrativeembodiment. Although a media gateway executes the tasks of theillustrative embodiment, in some alternative embodiments another type ofdata-processing system can be used to execute those tasks, as those whoare skilled in the art will appreciate. Furthermore, in accordance withthe illustrative embodiment, media gateway 101-p communicates with mediagateway controller 103 via the H.248 protocol, but as those who areskilled in the art will appreciate, in some alternative embodimentsmedia gateway 101-p can communicate in accordance with a different typeof call-control protocol and can handle datagram packets other thanInternet Protocol packets. In any event, it will be clear to thoseskilled in the art, after reading this specification, how to make anduse media gateway 101-p.

As depicted, media gateway 101-1 is interconnected with a plurality ofdifferent types of networks, including Internet Protocol Packet Network102, Public Switched Telephone Network 105, and local enterprise network107. Internet Protocol packet network 102 comprises one or moretransmission-related nodes such as routers that are used to direct datapackets from one or more sources to the correct destinations of thosepackets. Network 102 is capable of handling, in well-known fashion,Internet Protocol-based messages that are transmitted among two or moreInternet Protocol-capable devices such as (i) one or more IP terminals104-1 through 104-Q and (ii) a media gateway such as gateway 101-1, orbetween media gateway controller 103 and a media gateway. PublicSwitched Telephone Network 105 comprises one or moretransmission-related nodes such as switches that are used to directcall-related signals from one or more sources to the correctdestinations of those signals. Network 105 is capable of handling, inwell-known fashion, either analog or digital bearer information incircuit-switched calls among two or more devices such as (i) one or morePSTN terminals 106-1 through 106-S and (ii) media gateway 101-1. Localenterprise network 107 provides for local distribution of analogsignals, such as in an enterprise system, and comprises wiring betweenmedia gateway 101-1 and analog terminals 108-1 through 108-T.

As those who are skilled in the art will appreciate, telecommunicationssystem 100, and in particular media gateway 101-p, is capable in somealternative embodiments of handling other types of networks and othercombinations of networks than depicted. Furthermore, in some alternativeembodiments, each network might in turn comprise additional networks,such as cellular telephone networks and local area networks that areeither wired or wireless. For example, in some embodiments network 102might comprise a local area network (e.g., of a business enterprise,etc.), in which one or more of IP terminals 104-1 through 104-Q operate.

Media gateway controller 103 is a data-processing system that comprisesmedia gateway controller functionality that is known in the art,controlling media gateways 101-1 through 101-P. Media gateway controller103 provides the call control and signaling functionality for each mediagateway 101-p, in well-known fashion. Controller 103 communicates withmedia gateways 101-1 through 101-P via the H.248 protocol, but as thosewho are skilled in the art will appreciate, in some alternativeembodiments controller 103 can communicate in accordance with adifferent type of call-control protocol.

In accordance with the illustrative embodiment, controller 103 isphysically discrete from media gateways 101-1 through 101-P. However, asthose who are skilled in the art will appreciate, in some alternativeembodiments, the functionality of controller 103 and the functionalityof one or more gateways 101-1 through 101-P might co-exist with eachother (i.e., by sharing the same processor, memory, or other resources).In any event, it will be clear to those skilled in the art, afterreading this specification, how to make and use media gateway controller103.

FIG. 1 also depicts multiple telecommunications terminals of varioustypes. Internet Protocol-capable endpoints such as SIP desksets andlaptop-based or desktop-based softphones are represented by terminals104-1 through 104-Q. Plain Old Telephone Service (POTS) terminals,Integrated Services Digital Network (ISDN) phones, cell phones, andother PSTN-associated terminals are represented by terminals 106-1through 106-S. Analog enterprise desksets are represented by terminals108-1 through 108-T. As those who are skilled in the art willappreciate, the present invention is also applicable to othercombinations of terminals than depicted.

FIG. 2 depicts the salient components of media gateway 101-p, inaccordance with the illustrative embodiment of the present invention.Media gateway 101-p comprises main controller 201, memory 202, packetprocessor/interface 203, analog telephone interface 204, switchedtelephone network interface 205, and time division multiplexed (TDM) bus206, interconnected as shown.

Main controller 201 is a general-purpose processor that is capable ofcontrolling processor/interface 203, interface 204, interface 205, andTDM bus 206. Main controller 201 is also capable of executinginstructions stored in memory 202, reading data from and writing datainto memory 202, and executing the tasks described below and withrespect to FIGS. 4 through 7. In some alternative embodiments of thepresent invention, main controller 201 might be a special-purposeprocessor. In any event, it will be clear to those skilled in the art,after reading this specification, how to make and use main controller201.

Memory 202 stores the instructions and data used by main controller 201.Memory 202 might be any combination of dynamic random-access memory(RAM), flash memory, disk drive memory, and so forth. It will be clearto those skilled in the art, after reading this specification, how tomake and use memory 202.

Packet processor/interface 203 receives Internet Protocol datagrampackets from packet network 102, converts the information encoded in thepackets, and forwards the converted information to TDM bus 206, inwell-known fashion. Packet processor/interface 203 also receives timedivision multiplexed packets from TDM bus 206, converts the informationencoded in the packets, and forwards the converted information to packetnetwork 102, in well-known fashion. The salient components of packetprocessor/interface 203 are described below and with respect to FIG. 3.It will be clear to those skilled in the art, after reading thisspecification, how to make and use packet processor/interface 203.

Analog telephone interface 204 receives signals from local enterprisenetwork 107 and forwards the information encoded in those signals to TDMbus 206, in well-known fashion. Interface 204 also receives signals fromTDM bus 206 and forwards the information encoded in those signals tonetwork 107, in well-known fashion. It will be clear to those skilled inthe art, after reading this specification, how to make and use analogtelephone interface 204.

Switched Telephone Network interface 205 receives signals from PSTN 105and forwards the information encoded in those signals to TDM bus 206, inwell-known fashion. Interface 205 also receives signals from TDM bus 206and forwards the information encoded in those signals to network 105, inwell-known fashion. It will be clear to those skilled in the art, afterreading this specification, how to make and use interface 205.

TDM bus 206 carries isochronous traffic between processor/interface 203and interface 204 or 205, in well-known fashion. It will be clear tothose skilled in the art, after reading this specification, how to makeand use TDM bus 206.

FIG. 3 depicts the salient components of packet processor/interface 203,in accordance with the illustrative embodiment of the present invention.Processor/interface 203 comprises unit controller 301 and signalprocessing units 302-1 through 302-M, wherein M is a positive integer,and are interconnected as shown. In turn, each signal processing unit302-m, for m=1 through M, comprises digital signal processors 303-m-1through 303-m-N, wherein N is a positive integer.

Unit controller 301 is a general-purpose processor that is capable ofcontrolling signal processing units 302-1 through 302-M. Unit controller301 is also capable of executing the tasks described below and withrespect to FIGS. 4 through 7. As those who are skilled in the art willappreciate, after reading this specification, in various embodimentsunit controller 301 might execute all of the tasks described below oronly some of those tasks with main controller 201 executing the rest, ormain controller 201 instead might execute all of those tasks.Furthermore, in some alternative embodiments of the present invention,unit controller 301 might be a special-purpose processor. In any event,it will be clear to those skilled in the art, after reading thisspecification, how to make and use unit controller 301.

Signal processing unit 302-m is capable of converting the packets itreceives, either from packet network 102 or TDM bus 206, into adifferent, predetermined format. Since a packet stream that is received,for example, from the IP packet network 102 comprises data packets andcontrol packets, which contain addressing information, unit 302-mconverts the received packets to a voice data stream of isochronouspackets that are suitable for TDM bus 206, while processing the controlpackets. Unit 302-m must perform the conversion in a timely manner tominimize the possibility of packet loss. To handle all of the packetsresponsively and without delay or jitter, unit 302-m uses digital signalprocessors 303-m-1 through 303-m-N, which are dedicated devices that arecapable of the high-speed packet processing that is required for theconversion. Each digital signal processor 303-m-n is capable ofproviding K processing resources such as processing channels, wherein Kis a positive integer, in order to handle multiple calls and thedifferent conversion formats across the calls. For example, eachconversion format might be distinguished by a different packet size atthe datagram packet side of the processing. Protocol standards existthat govern the different packet sizes, as well as other properties suchas compression and decompression (as specified in G.711, G.729, and soforth), encryption, and redundancy. Similarly, unit 302-m must alsoperform the conversion in the other direction from a time divisionmultiplexed stream to Internet Protocol packets in a timely manner, aswell as control the interval between the creation and transmission ofpackets.

Unit 302-m is uniquely addressable via its own Internet Protocoladdress. Furthermore, each processing resource of digital signalprocessor 303-m-n within unit 302-m is accessible by using a UserDatagram Protocol (UDP) port number that has been assigned to it by itshost media gateway. The UDP port numbers can be reused across signalprocessor units 302-1 through 302-M because each signal processor unithas a different port number address space, since each unit has its ownInternet Protocol address assigned to it. Therefore, each processingresource of digital signal processor 303-m-n is uniquely addressable bythe combination of both (i) the Internet Protocol address of unit 302-mand (ii) the port number assigned to the resource. As those who areskilled in the art will appreciate, in some alternative embodiments, adifferent addressing scheme can be used-for instance, one that uses SIPaddresses with port numbers or one that uses IP addresses with aresource identifier other than UDP port number.

It will be clear to those skilled in the art, after reading thisspecification, how to make and use signal processing unit 302-m and itsdigital signal processors 303-m-1 through 303-m-N.

FIG. 4 depicts a message flow diagram of an information exchange betweenInternet Protocol telecommunications terminal 104-1, media gatewaycontroller 103, and media gateway 101-1, and is intended to provide ageneral background of the message exchange that occurs during a callsetup sequence that involves these devices. It will be clear to thoseskilled in the art which events depicted in FIG. 4 can occursimultaneously or in a different order than that depicted.

At event 401, terminal 104-1 receives an indication (e.g., an “off hook”condition, etc.) from its user that the user wishes to make a call.

In response, terminal 104-1 transmits message 402 to media gatewaycontroller 103, requesting that a call be set up between terminal 104-1and the specified other endpoint, such as one of the PSTN terminals(e.g., terminal 106-3, etc.).

Media gateway controller 103 then transmits message 403 to theparticular media gateway that is able to provide access to the calledterminal, in this case gateway 101-1. Message 403 is a request bycontroller 103 to start a negotiation for signal processing resourcesthat are present at gateway 101-1. Message 403 comprises the type ofinformation coding that IP terminal 104-1 can handle, such as G.711and/or G.729 coding, as well as other information relevant to both thecall and to media gateway 101-1.

Media gateway 101-1, in response, transmits message 404 to controller103, providing a survey of the available resources that can serve thecall. The information contained in message 404 comprises the InternetProtocol address and as the UDP port number of each available resource,along with type of information that the available resources are able toprocess.

Upon receiving message 404, controller 103 selects a processing resourcefrom those identified in message 404 to serve the call. Meanwhile, inthe illustrative scenario, a malfunction is detected at event 405 atgateway 101-1 that affects the very same processing resource selected bycontroller 103.

Media gateway controller 103 notifies gateway 101-1 via message 406 andIP terminal 104-1 via message 407 of its selection of the particularprocessing resource that will serve the call. Gateway 101-1 normallyuses the information in message 406 to determine which processingresource is to be allocated to the call. IP terminal 104-1 uses theinformation in message 407 to determine, as part of the call, (i) whereto send its outgoing packets going forward, (ii) which incoming packetsare intended for the terminal, and (iii) how to process the packets.

In some embodiments, media gateway 101-1 might then transmit message 408to media gateway controller 103, notifying the controller that an errorhas occurred.

FIG. 5 depicts a first flowchart of the salient tasks that involvereassigning a second processing resource to handle a call's packetstream after a first resource has been affected by a malfunction, inaccordance with a first variation of the illustrative embodiment of thepresent invention. The described tasks are optimized to place a priorityon finding a processing resource that is available within the addressspace of the first Internet Protocol address (i.e., the same address asthat of the faulty processing resource). The advantage of this approachis that media controller 103 does not have to be notified of a change inprocessing resource, provided that the change occurs within the domainof the same Internet Protocol address already selected by thecontroller. For illustrative purposes, a processing resource of digitalsignal processor 303-1-2 at media gateway 101-1 is the resource that isaffected by the malfunction. As those who are skilled in the art willappreciate, some of the tasks that appear in FIG. 5 can be performed inparallel or in a different order than that depicted.

At task 501, media gateway 101-1 transmits to media gateway controller103 a message that comprises at least a first Internet Protocol address.This message is the same as message 404 described above, which containedone or more Internet Protocol addresses that identified availableprocessing resources for a call. The address is significant, in thatprocessor 303-1-2 is addressable by the first Internet Protocol address.

At task 502, gateway 101-1 detects a malfunction that affects a firstprocessing resource in processor 303-1-2.

At task 503, gateway 101-1 receives from media gateway controller 103 anindication that the first processing resource has been assigned bycontroller 103 to handle a packet stream, wherein the first processingresource is addressable by a first port number.

At task 504, gateway 101-1 determines whether a second signal processorthat is also addressable by the first Internet Protocol address isavailable to handle the packet stream. The determination occurs as theresult of (i) the detection of the first malfunction at task 502 and(ii) the receiving of the indication at task 503. The determinationitself is based on criteria that include: i) the capabilities that havebeen assigned to handle the first packet stream at signal processor303-1-2 and ii) the capabilities of the telecommunications terminal thatis originating the first packet stream (e.g., terminal 104-1, etc.). Forexample, gateway 101-1 might proceed to identify a processing resourcewith a different capability than before, but one that is stillcompatible with the terminal.

At task 505, if the second signal processor is available, per thecriteria considered at task 504, then task execution proceeds to task506. If not, task execution proceeds to task 508.

At task 506, gateway 101-1 selects a second processing resource tohandle the packet stream, based on criteria that include: i) thecapabilities identified to handle the packet stream at processor303-1-2; and ii) the capabilities of IP terminal 104-1 (i.e., theterminal originating the packet stream). For example, gateway 101-1might preferentially select a resource that can provide that samecapability as before over a resource that cannot.

At task 507, gateway 101-1 reassigns the first port number to the secondprocessing resource, in accordance with the illustrative embodiment.This has the effect of routing incoming packets from network 102 to thenew processing resource, which successfully completes the call, insteadof replying with an error that indicates the malfunctioning resource,which would cause the call to be renegotiated or terminated. It will beclear to those skilled in the art how media gateway 101-1 assigns andreassigns port numbers dynamically. Task execution then ends.

At task 508, gateway 101-1 transmits a message to media gatewaycontroller 103, wherein the message comprises at least a second InternetProtocol address which is usable to address a different signalprocessing unit than the unit that processor 303-1-2 is a part of. Thismessage is the same as message 701 that is described below and withrespect to FIG. 7.

At task 509, gateway 101-1 receives from media gateway controller 103 anindication that a processing resource has been assigned to handle thepacket stream, wherein the assigned processing resource is addressableby the second Internet Protocol address or by another specified addresswhich controller 103 selected from those provided at task 508. Gateway101-1 also receives a port number from controller 103, which port numbercoincidentally could be the same as the first port number. Taskexecution then ends.

FIG. 6 depicts a second flowchart of the salient tasks that involvereassigning a second processing resource to handle a call's packetstream after a first resource has been affected by a malfunction, inaccordance with a second variation of the illustrative embodiment of thepresent invention. The described tasks are optimized to place a priorityon finding the best processing resource for the call's packet stream,even if the resource is not within the address space of the firstInternet Protocol address. For illustrative purposes, a processingresource of digital signal processor 303-1-2 at media gateway 101-1 isthe resource that is affected by the malfunction. As those who areskilled in the art will appreciate, some of the tasks that appear inFIG. 6 can be performed in parallel or in a different order than thatdepicted.

At task 601, media gateway 101-1 transmits to media gateway controller103 a message that comprises at least a first Internet Protocol address.This message is the same as message 404 described above, which containedone or more Internet Protocol addresses that identified availableprocessing resources for a call. The address is significant, in thatprocessor 303-1-2 is addressable by the first Internet Protocol address.

At task 602, gateway 101-1 detects a malfunction that affects a firstprocessing resource in processor 303-1-2.

At task 603, gateway 101-1 receives from media gateway controller 103 anindication that the first processing resource has been assigned bycontroller 103 to handle a packet stream, wherein the first processingresource is addressable by a first port number.

At task 604, gateway 101-1 selects a second processing resource tohandle the packet stream. The selection occurs as the result of (i) thedetection of the first malfunction at task 602 and (ii) the receiving ofthe indication at task 603. The selection itself is based on criteriathat include: i) the capabilities identified to handle the packet streamat processor 303-1-2; ii) the capabilities of IP terminal 104-1 (i.e.,the terminal originating the packet stream); and iii) the InternetProtocol address of processor 303-1-2.

At task 605, gateway 101-1 checks whether a second signal processor thatis also addressable by the first Internet Protocol address is availableto handle the packet stream. If the second signal processor isavailable, then task execution proceeds to task 606. If not, taskexecution proceeds to task 607.

At task 606, gateway 101-1 reassigns the first port number to the secondprocessing resource, in accordance with the illustrative embodiment.This has the effect of routing incoming packets from network 102 to thenew processing resource, instead of to the malfunctioning resource. Taskexecution then ends.

At task 607, gateway 101-1 transmits a message to media gatewaycontroller 103, wherein the message comprises at least a second InternetProtocol address which is usable to address a different signalprocessing unit than the unit that processor 303-1-2 is a part of. Thismessage is the same as message 701 that is described below and withrespect to FIG. 7. In accordance with the illustrative embodiment,gateway 101-1 provides exactly one IP address (i.e., that of theselected signal processor) to controller 103. In some alternativeembodiments, gateway 101-1 provides more than one Internet Protocoladdress to the controller when more than one set of attributes can beused by the IP terminal as identified in the original negotiationmessage (i.e., message 403) sent by the media gateway controller.

At task 608, gateway 101-1 receives from media gateway controller 103 anindication that a processing resource has been assigned to handle thepacket stream, wherein the assigned processing resource is addressableby the second Internet Protocol address or by another specified addresswhich controller 103 selected from those provided at task 607. Gateway101-1 also receives a port number from controller 103, which port numbercoincidentally could be the same as the first port number. Taskexecution then ends.

FIG. 7 depicts a message flow diagram of an information exchange betweenmedia gateway 101-1 and message gateway controller 103, in accordancewith the illustrative embodiment of the present invention. The events inFIG. 7 occur as the result of task 508 or 607 having been invoked. Itwill be clear to those skilled in the art which events depicted in FIG.7 can occur simultaneously or in a different order than that depicted.

Message 701 is transmitted by media gateway 101-1 to media gatewaycontroller 103, in accordance with the illustrative embodiment of thepresent invention. Gateway 101-1 uses message 701 to request controller103's approval to use a different processing resource than a resourcepreviously identified (i.e., in message 406) to handle a particularpacket stream. Message 701 specifies a different Internet Protocoladdress than the one being used for the packet stream, as well as anassociated UDP port number. In some embodiments, message 701 specifiesmore than one IP address and more than one UDP port number.

Message 702 is transmitted by media gateway controller 103 to mediagateway 101-1, in response to message 701. Controller 103 uses message702 to indicate to gateway 101-1 that the request has been accepted andthat the packet stream going forward will be associated with the newInternet Protocol address and port number. The new addressinginformation corresponds to a digital signal processor on a differentsignal processing unit at gateway 101-1. Controller 103 also transmitsmessage 703 to the endpoint associated with the packet stream, in thiscase Internet Protocol telecommunications terminal 104-1. Terminal 104-1then uses the new addressing information to determine where to send itspackets going forward and which packets are the ones that the terminalshould be receiving, as part of its call, given that the packet streamis being moved to a different processing resource at gateway 101-1 witha different IP address and possibly a different UDP port.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by those skilled in the artwithout departing from the scope of the invention. For example, in thisSpecification, numerous specific details are provided in order toprovide a thorough description and understanding of the illustrativeembodiments of the present invention. Those skilled in the art willrecognize, however, that the invention can be practiced without one ormore of those details, or with other methods, materials, components,etc.

Furthermore, in some instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the illustrative embodiments. It is understood that thevarious embodiments shown in the Figures are illustrative, and are notnecessarily drawn to scale. Reference throughout the specification to“one embodiment” or “an embodiment” or “some embodiments” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment(s) is included in at least one embodimentof the present invention, but not necessarily all embodiments.Consequently, the appearances of the phrase “in one embodiment,” “in anembodiment,” or “in some embodiments” in various places throughout theSpecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, materials, orcharacteristics can be combined in any suitable manner in one or moreembodiments. It is therefore intended that such variations be includedwithin the scope of the following claims and their equivalents.

1. A method comprising: detecting a first malfunction, wherein saidfirst malfunction affects a first processing resource in a first signalprocessor in a first data-processing system; receiving a firstindication, which indicates that said first processing resource has beenassigned to handle a first packet stream, wherein said first processingresource is addressable by a first port number, and wherein said firstport number exists in the address space of a first plurality of signalprocessors that comprises said first signal processor; selecting asecond processing resource to handle said first packet stream, whereinthe selection occurs as the result of (i) the detection of said firstmalfunction and (ii) the receiving of said first indication; andreassigning said first port number to said second processing resource.2. The method of claim 1 wherein said second processing resource is in asecond signal processor that is in said first plurality of signalprocessors.
 3. The method of claim 1 further comprising: detecting asecond malfunction, wherein said second malfunction affects a thirdprocessing resource in said first signal processor; receiving a secondindication, which indicates that said third processing resource has beenassigned to handle a second packet stream, wherein said third processingresource is addressable by a second port number, and wherein said secondport number exists in the address space of said first plurality ofsignal processors; selecting a fourth processing resource to handle saidsecond packet stream, wherein the selection occurs as the result of (i)the detection of said second malfunction and (ii) the receiving of saidsecond indication; and reassigning said second port number to saidfourth processing resource.
 4. The method of claim 3 wherein said secondprocessing resource is in said first signal processor, and wherein saidfourth processing resource is in a second signal processor that is insaid first plurality of signal processors.
 5. The method of claim 1further comprising transmitting, prior to the detection of said firstmalfunction, a first message to a second data-processing system, whereinsaid first message comprises at least a first Internet Protocol address,and wherein said first plurality of signal processors is addressable bysaid first Internet Protocol address.
 6. The method of claim 5 whereinsaid first data-processing system is a media gateway, and wherein saidsecond data-processing system is a media gateway controller, and whereinsaid first message is transmitted in accordance with the H.248 protocol.7. The method of claim 1 wherein the selection of said second processingresource is based on at least one of: i) the capabilities being used tohandle said first packet stream at said first signal processor, and ii)the capabilities of a telecommunications terminal that is originatingsaid first packet stream.
 8. The method of claim 7 wherein said firstpacket stream is of a Voice over Internet Protocol call that involvessaid telecommunications terminal, and wherein said first port number isa Universal Datagram Protocol port number.
 9. A method comprising:detecting a first malfunction, wherein said first malfunction affects afirst processing resource in a first signal processor in a firstdata-processing system; receiving a first indication, which indicatesthat said first processing resource has been assigned to handle a firstpacket stream, wherein said first processing resource is addressable bya first port number, and wherein said first port number exists in theaddress space of a first plurality of signal processors that comprisessaid first signal processor, and wherein said first plurality of signalprocessors is addressable by a first Internet Protocol address;determining whether a second signal processor that is in said firstplurality of signal processors is available to handle said first packetstream, wherein the determination occurs as the result of (i) thedetection of said first malfunction and (ii) the receiving of said firstindication; and when said second signal processor is unavailable,transmitting a first message to a second data-processing system, whereinsaid first message comprises at least a second Internet Protocoladdress, and wherein a second plurality of signal processors thatexcludes both said first signal processor and said second signalprocessor is addressable by said second Internet Protocol address. 10.The method of claim 8 further comprising: detecting a secondmalfunction, wherein said second malfunction affects a second processingresource in said first signal processor; receiving a second indication,which indicates that said second processing resource has been assignedto handle a second packet stream, wherein said second processingresource is addressable by a second port number, and wherein said secondport number exists in the address space of said first plurality ofsignal processors; selecting a third processing resource to handle saidsecond packet stream, wherein the selection occurs as the result of (i)the detection of said second malfunction and (ii) the receiving of saidsecond indication; and reassigning said second port number to said thirdprocessing resource.
 11. The method of claim 10 wherein said secondprocessing resource is in said first signal processor.
 12. The method ofclaim 10 wherein said second processing resource is in said secondsignal processor.
 13. The method of claim 9 further comprisingtransmitting, prior to the detection of said first malfunction, a secondmessage to said second data-processing system, wherein said secondmessage comprises at least said first Internet Protocol address.
 14. Themethod of claim 9 further comprising receiving a second indication,which indicates that a third processing resource has been assigned tohandle said first packet stream, wherein said third processing resourceis addressable by a second port number, and wherein said second portnumber exists in the address space of a second plurality of signalprocessors that comprises said third signal processor, and wherein saidsecond plurality of signal processors is addressable by said secondInternet Protocol address.
 15. The method of claim 9 wherein thedetermination of whether said second processing resource is available isbased on at least one of: i) the capabilities that have been assigned tohandle said first packet stream at said first signal processor, ii) thecapabilities of a telecommunications terminal that is originating saidfirst packet stream, and iii) said first Internet Protocol address. 16.The method of claim 15 wherein said first packet stream is of a Voiceover Internet Protocol call that involves said telecommunicationsterminal, and wherein said first port number is a Universal DatagramProtocol port number.
 17. The method of claim 9 wherein said firstdata-processing system is a media gateway, and wherein said seconddata-processing system is a media gateway controller, and wherein saidfirst message is transmitted in accordance with the H.248 protocol. 18.A method comprising: receiving a first indication, which indicates thata first processing resource in a first signal processor at a firstdata-processing system has been assigned to handle a first packetstream, wherein said first processing resource is addressable by a firstport number, and wherein said first port number exists in the addressspace of a first plurality of signal processors that comprises saidfirst signal processor, and wherein said first plurality of signalprocessors is addressable by a first Internet Protocol address;selecting a second processing resource at said first data-processingsystem to handle said first packet stream, wherein the selection occursas the result of: i) a malfunction that affects said first processingresource, and ii) the receiving of said first indication, and whereinthe selection is based on at least one of: i) the capabilities that havebeen assigned to handle said first packet stream at said first signalprocessor, ii) the capabilities of a telecommunications terminal that isoriginating said first packet stream, and iii) said first InternetProtocol address; and when said second processing resource is in asecond signal processor that is in a second plurality of signalprocessors that is addressable by a second Internet Protocol address,transmitting a first message to a second data-processing system, whereinsaid first message comprises: i) said second Internet Protocol address,and ii) a pointer to said second processing resource, and wherein saidsecond plurality of signal processors excludes said first signalprocessor.
 19. The method of claim 18 further comprising receiving asecond indication, which indicates that a third processing resource hasbeen assigned to handle said first packet stream, wherein said thirdprocessing resource is addressable by a second port number, and whereinsaid second port number exists in the address space of said secondplurality of signal processors.
 20. The method of claim 19 wherein saidsecond processing resource and said third processing resource are thesame.
 21. The method of claim 19 wherein said second processing resourceand said third processing resource are different.
 22. The method ofclaim 18 wherein said first packet stream is of a Voice over InternetProtocol call that involves said telecommunications terminal, andwherein said first port number is a Universal Datagram Protocol portnumber.
 23. The method of claim 18 wherein said first data-processingsystem is a media gateway, and wherein said second data-processingsystem is a media gateway controller, and wherein said first message istransmitted in accordance with the H.248 protocol.